Switching device using flat contact pieces



Aug. 2, 1 966 w. HOLZER 3,264,442

SWITCHING DEVICE USING FLAT CONTACT PIECES Filed NOV. 12, 1964 WALTER HOL 25/? ATTURNEYS United States Patent 3,264,442 SWITCHING DEVICE USING FLAT CONTACT PIECES Walter Holzer, Drosteweg 19, Meersburg, Bodensee, Germany Filed Nov. 12, 1964', Ser. No. 416,403 Claims priority, application Germany, Nov. 27, 1963,

7 Claims. 61. 200-166) This invention relates to flat contacts having the form of elongated stamped members which are positively pressed by a spring against conductive surfaces or contacts. One end of the said stamped part is designed as a bearing and, during the switching movements of the stamped part, rolls along the conductive coating, the stamped part being guided in an edgewise guide.

A flat contact of this type is already known which. is advantageously used as a switching element for printed circuits, because, with the form according to the invention, numerous soldered connections may be saved and assembly simplified.

However, it has become manifest that the edge/wise guiding of the stamped .part presents difficulties and that, for a reliable edgewise guide, additional guide elements have to be provided which advantageously increase the size of the fiat contact. Furthermore, the individual component parts of this flat contact, such as for example the aforesaid edgewise guide, the thrust spring and the stamped part, have to be assembled stepwise, which, having regard to the small dimensions of these components, makes great requirements of the assembly personnel, individual small components very frequently being lost.

It is an object of the present invention to provide an improved flat contact which, although avoiding the above described disadvantages, can be simply and cheaply manufactured with wide manufacturing tolerances and wherein assembly is not only substantially simplified but, moreover, any danger of losing individual components is excluded.

It is a further object of this invention to provide greater operational reliability as compared with the known flat contacts, and to achieve better contact making lwithout thereby in any way increasing the manufacturing costs.

According to the invention, the tasks imposed are resolved in a flat contact haw/ing the form of an elongated stamped part, which is pressed operatively by a spring against conductive surfaces, one end of the stamped part taking the shape of a bearing and, during switching movements of the stamped part in an edgewise guide, following the conductive surface, by said edgewise guide being fitted with 'stop and self-cleaning contact surfaces for the bearing of the stamped part and being formed with this by reason of the spring into an operatively interlocked assembly unit with connecting elements, the fitment length of which corresponds substantially to the length of the stamped part.

By reason of this main feature of the invention, the individual components of the flat contacts are interlocked into one assembly unit already prior to assembly so that the aforesaid unit can, without further labor expenditure, be incorporated complete into a switch or other electrical device. This means a saving not only on working time but, moreover, no individual components can be lost during assembly. Furthermore, there is the great advantage that this novel flat contact formed according to the invention can find application not only in connection with printed circuits but has the form of an independent switch, the assembly unit already having connecting elements through which the current can be supplied. Yet a further advantage resides in the short fitment length, so

32%,442 Patented August 2, 1966 "ice that the flat contact can be used even where the space is very limited. Whereas with the conventional embodiments of fiat contacts having following bearings, the contact faces were subject to the risk of corrosion, this is obviated in the fiat contact formed according to the invention by having self-cleaning contact faces.

This is achieved, according to the invention by the bearing being against a contact surface which is arranged at an angle to the direction of thrust of the spring and being limited by stop faces, the reciprocal distance between which leaving a clearance in respect of the width of the bearing so that the latter can be displaced on the contact face under the action of the spring pressure which is directed slantwise thereto, so that, with every switching movement, friction occurs between the bearing and the contact face, which causes the same to be automatically cleaned.

In a preferred embodiment of the invention, the edgewise guide, including the stop and contact faces, is of thin-Walled section with a pressed-out guide lug, the stamped member being arranged between this and the wall of the section.

By virtue of this construction of the invention, the edgewise guide, including the stop, contact and guide faces, can be economically manufactured in one operation.

In order to be able to compose the individual elements into one postively interlocked assembly unit, a recess is provided in the shaped section to take a spring which bears on the one hand against the said shaped section and on the other against the stamped member, a locking pin being arranged in the recess for one end of the spring whilst into the other end of the spring a locking protuberance on the stamped member engages.

By reason of this construction, according to the invention, not only is a positive but also a partly operative interlocking of the individual components achieved, so that the assembled unit can be mounted, transported, and incorporated into appliances.

Thanks to the thin-walled construction of the shaped section and the stamped part, it is only the diameter of the small-dimension spring which determines the width of the assembled unit, so that, where there is little space, a large number of units according to the invention can be arranged parallel with one another, which is not the case with any of the known flat contacts which have a substantially greater width.

In order to bring about the already mentioned inclination of the self-cleaning contact face as opposed to the direction of spring pressure, it is possible either to ar range of the locking pin and locking protuberance substantially on the same vertical in respect of the central line through the longitudinal axis of the stamped member or to form the contact face at an angle thereto, or to construct the contact face substantially parallel with the longitudinal middle line, the locking pin and locking protuberance being then each arranged on different verticals in respect of the longitudinal middle line.

Both of these above mentioned embodiments guarantee optionally an inclined position of the contact face to the direction of spring thrust, so that, when the stamped part is displaced longitudinally in the magnitude of the clearance between the bearing and the stop faces, the bearing, by reason of the action of the operated cam, performs a self cleaning frictional movement against the direction of spring pressure and on the contact face.

For greater understanding of the invention, reference should be made to the ensuing description, in conjunction with the attached drawings which, in various figures, illustrate a preferred embodiment of the flat contact according to the invention and reveal further advantages and features of the invention.

FIG. .1 illustrates diagrammatically the side elevation of a fiat contact formed according to the invention, incorporated in a switch'housing.

FIG. 2 shows a cross-section along the line IIII of 1 FIG. 1.

FIG. 3 shows on an enlarged scale the flat contact in FIGS. 1 and 2 during operation by a switching cam.

FIG. 4 likewise in enlarged scale, shows a part ofthe flat contact of FIG. 3, but with a different spring arrangement.

FIG. 5 shows diagrammatically the perspective view of an assembly unit of the flat contact according to the in-".

vention, ready for fitment.

-FIG..-1 shows the flat contact in the form of an elonintermediate space in which the stamped part 1 is'ac-,

commodated. It will be seen that the edgewise guides has a recess 7 in which is arranged a spring 8 which bears at one end against a locking pin'9'in the edgewise guide 5 and at the other against a locking protuberance 10 on the stamped part 1. According to FIG. 1, the scanning contact 2 rests on a stationary contact 11, so thatthe bearing 3, under the pressure of the spring 8, is pressed 4 embodiment of the flat contactaccording to the invention, wherein the contact face 4 is substantially parallel with the longitudinal central line 25,?whilst-the locking pin andlocking protuberance .IO are-each on different verticals 26*, 27 intelation to the longitudir'lalcentralline 25,, so that the spring 8 is given a slanting, position, the

direction of thrust being designated 28, so that the 7 bearing 3, when inoperative, assumes the position shown in ch aim-dotted lines in FIG. 4 with a self-cleaning frictional action as the same is passed :over the contact .face 4,

whereas, when the Zstamped part 1!.is operated in the manner described above, in' the direction of arrow 22,

a displacement occurs against thepressure of spring'8 into the position shown in solid lines.

positively against the contact face 4. The edgewise guide 5 is held in the rear wall 13 of a switch housing 14,-

from the front wall 15 of which protrudes lug 16of the stamped part 1 through an aperture 17. Itiwill be seen that the length of the flat contact, by reason of the design of the edgewise guide 5 according to the invention, corresponds substantially to the length of the stamped part 1.

In FIG. 2, a cross-section taken along the line IIII' of FIG. 1 is shown and it is seen that the width of the fiat contact, with stamped part 1 and edgewise guide 5 is essentially determined by the diameter of the small dimensioned spring 8, so that, by reason of this minimum width, a plurality of fiat contacts constructed according to the invention can be accommodated, even where the space available is restricted.

As can be better appreciated from the detail in FIG. 3,

displaced in this direction, so that the bearing 3 slides;

with a self-cleaning frictional actionover the contact face 4 from the position illustrated in chain-dotted lines into the'position illustrated by solid lines in FIG. 3.

When the lug 16 is released by the switching cam 21;

the pressure component 23 of a spring pressure in the direction 18 has the effect of causing the bearing 3 to slide back into the position shown in FIG. 3 in chaindotted lines, the stamped part 1 being displaced against the direction of the arrow 22 and consequently also of producing a self-cleaning frictional action between the scanning contact 2 and the stationary contact. 11, so-that,

with the design of flat contact according to the invention, 7

it is possible to speak of a highly eflicient self-cleaning elfect.

Whereas, in FIG. 3 the locking pin '9 and locking pro- 1 tuberance 10 are on a common vertical 24 to the longitudinal central line 25 through the stamped part 1 :and the contact face 4 is arranged slantwise to'the longitudinal central line 25, FIG. 4 shows a possible modified FIG. 5 shows diagrammatically the perspective viewof the individual, components of the flat contact which, by reason of the design accordingto the invention, can

be composed into a positively, and partly even operatively 1 interlocked assembly unit 29. An, assembly unit each as this can .be mountedv and transported without the danger of any ,of the individual components being1ost.1 For: incorporation in an electrical unit, for example a,

switch housing, it is only necessary to push the connecting element. 12 through a slot in-the switch housing or in a base plate and twistit in known manner.v The lower is then fedto the stamped part 1 through the connecting element 12, the edgewise guide 5, the contact face 4 thereof, to bearing 3. Shunting :is possible through the wall of the, edgewise guide 5 and the guide lug 6.:if, bysuitable angling of the shaped section, a slight inclination to theplane of the switching movement of the stamped part 1 can beqgiven tothe s ring S-sothat the stamped part is; pressed either slightly against ,the

guide lug 6 or against the wall of the edgewise guide 5.

Although the description and the drawings show that the flat contactproduced according tothe inventioncan,

in the form of an assembly unit, be advantageously disposed in flat switch housings, it mustbe established here that-it is: readily possible-to combine-the saidassembly unit with printed circuits, whenthe connecting; elements 121are passed through the carrierplates' of the printed circuits, twisted and soldered to the. conductivecoatings or connected therewith in other, conductively suitable manner. It is also possible to arrange the assembly unit 29, by meansof the connecting elements 12.to.a top printed circuit and to have the scanning contact21coopcrate with the conductive surfacing of a bottom printed circuit arranged parallel to the top printed, circuit, an arrangement which, on structural grounds, has been shown to be advantageous.

By reason of its space-saving arrangement, the flat contact according to the invention, in all its embodiments, is ideal in the event of the greatestpossible number of such switches needing to be simply and with a minimum of'assembly expenditure, accommodated in a limited space.

I claim:

1. A switching device comprising a stamped flat contact piece, one end of said fiat contact piece being adapted to act simultaneously as a bearing and as. a contact, and the other end of said contact piece having a cam follower portion adaptedtomest on a cam and having: a contact portion adapted to contact a counter contact :piece, a,

spring, said flat contact piece having a protuberance upon which said spring is positioned and an edgewise guide holding said contact-piece, said edgewise guide having stop faces and a self cleaning contact face, said bearing end of said flat contact piece resting on said .con tact face of said guide, said spring being connected to said guide whereby said flat contact piece, said spring and said guide form a positively connected interlocked assembly, the length of the assembly corresponding substantially to the length of said flat contact piece.

2. The switching device of claim 1 wherein said bearing end of said contact'piece rests against said contact face of said guide, said contact face being inclined with respect to the direction of pressure of said spring, said bearing end of said contact piece being limited by said stop faces of said guide, the distance between said stop faces being greater than the width of said contact piece bearing end so as to leave a clearance for said contact piece bearing end.

3. The switching device of claim 1 wherein said edgewise guide is a thin walled cut form having a punched out g-uide lug, said contact piece being positioned between said guide lug and out form wall of said guide.

4. The switching device of claim 3 wherein said out form guide is provided with a recess within which said spring is positioned, the respective ends of said spring being propped against said guide and said contact piece.

5. The switching .device of claim 4 wherein said guide has an interlocking lug disposed within said recess, said spring being positioned on said interlocking lug on said guide and on said protuberance on said contact piece.

6. The switching device of claim 5 wherein said lug on said guide and said protuberance on said contact piece are arranged on substantially the same vertical axis in relation to the longitudinal axis of the contact piece and wherein said contact face on said guide is formed at an angle to said longitudinal axis of said contact piece.

7. The switching device of claim 5 wherein said l'ug on said guide and said protuberance on said contact piece are arranged on different vertical axes in relation to the longitudinal axis of said contact piece and wherein said contact face on said guide is formed substantially parallel to said longitudinal axis of said contact piece such that the direction of pressure of said spring is oblique.

References Cited by the Examiner UNITED STATES PATENTS 3,032,617 5/1962 Holzer 200166 X ROBERT K. SCHAEFER, Primary Examiner.

ROBERT S. MACON, Examiner.

H. O. JONES, Assistant Examiner. 

1. A SWITCHING DEVICE COMPRISING A STAMPED FLAT CONTACT PIECE, ONE END OF SAID FLAT CONTACT PIECE BEING ADAPTED TO ACT SIMULTANEOUSLY AS A BEARING AND AS A CONTACT AND THE OTHER END OF SAID CONTACT PIECE HAVING A CAM FOLLOWER PORTION ADAPTED TO REST ON A CAM AND HAVING A CONTACT PORTION ADAPTED TO CONTACT A COUNTER CONTACT PIECE, A SPRING, SAID FLAT CONTACT PIECE HAVING A PROTUBERANCE UPON WHICH SAID SPRING IS POSITIONED AND AN EDGEWISE GUIDE HOLDING SAID CONTACT PIECE, SAID EDGEWISE GUIDE HAVING STOP FACES AND A SELF CLEANING CONTACT FACE, SADI BEARING END OF SAID FLAT CONTACT PIECE RESTING ON SAID CONTACT FACE OF SAID GUIDE, SAID SPRING BEING CONNECETED TO SAID GUIDE WHEREBY SAID FALT CONTACT PIECE, AND SPRING AND SAID GUIDE FORM A POSITIVELY CONNECTED INTERLOCKED ASSEMBLY, THE LENGTH OF THE ASSEMBLY CORRESPONDING SUBSTANTIALLY TO THE LENGTH OF SAID FLAT CONTACT PIECE. 